The present invention relates to a vehicle seat and, in particular, concerns a vehicle seat with temperature control.
U.S. Pat. No. 5,934,748 discloses a vehicle seat the backrest of which a fan means is provided, supplying air aspirated from the passenger compartment to the surface of the backrest pad by way of a heating means. In the part of the backrest pad to be occupied by the lumbar region of an occupant, a temperature sensor is provided for adjusting the seat xe2x80x9cclimate.xe2x80x9d A regulating means is provided, connected to the temperature sensor at the input end and to the fan means and heating means at the output end. In the regulating means, a control algorithm is stored, according to which both the heating means and the fan means are regulated relative to the temperature of the pad surface as measured by the temperature sensor. This requires a very complicated control algorithm, since both the operation of the heating means and the operation of the fan means must be readjusted by the user from time to time in selecting the desired seat temperature. Furthermore, there is the problem that the heating means is able to heat only a limited flow of air at a physiologically acceptable temperature level when temperatures in the interior of the vehicle are very low.
The present invention provides a vehicle seat having an improved design whereby the seat climate control is adapted to the internal temperature of the vehicle with a simplified control scheme.
In particular, the present invention provides a vehicle seat having at least one pad with an air-permeable surface area. An air-permeable heater element is arranged in the region of the air-permeable surface area of the pad to heat the surface area of the pad. The seat further includes a fan proximate the heating element to force air through the heating element and the surface area of the pad. A first temperature sensor detects the temperature of the surface area of the pad and/or the heating element. A second temperature sensor monitors the temperature of the air aspirated by the fan. A controller in operative communication with the first and second temperature sensors regulates the valve flow of air of the fan as a function of the second temperature sensor signal.
With the vehicle seat according to the present invention, the fan automatically adjusts the required volume flow of air through the pad as a function of the internal vehicle temperature. At low air temperatures, the fan delivers a small volume flow of air, whereas at high temperatures, it will deliver a large volume flow of air. This ensures that the volume flow of air can be heated to a physiologically acceptable temperature level even when the internal temperature of the vehicle is low.
An advantage of the present invention is that the temperature of the heater element is regulated independently of the fan operation. For this reason, a simple control algorithm can be employed for the heater as a function of the first temperature sensor.
The controller may regulate the volume flow of air on the basis of a characteristic curve representing a function of the temperature detected by the second temperature sensor. However, the characteristic curve may alternatively represent a function of the difference between the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor.
In one embodiment, at least the second temperature sensor is a negative temperature coefficient (NTC) sensor.
Advantageously, an operating scheme is provided by which the target temperature of the heating element can be set, and the fan can be switched on and off.
The information acquired by the second temperature sensor by way of the air inside the vehicle may be supplied by way of an electronic BUS system associated with the heating, ventilation and air-conditioning (HVAC) system of the vehicle. In this way, the HVAC system and seating system can communicate to share information, or the HVAC system can be provided additional temperature data from the seat system.
Other advantages and features of the invention will become apparent upon reading the following detailed description and appended claims, and upon reference to the accompanying drawings.